The original Idaho Territory included what we now call Montana and most of present-day Wyoming in 1863. By 1864 the Territory began to resemble the shape of the state we know today, and had 14 counties.
Those enormous counties got smaller as population grew and the need for government closer to home grew with it. Once a county was named, that name tended to stick, even through shrinkage. We lost only two names in the shuffle, Alturas and Logan.
Alturas was a county from February 4, 1864 to March 5, 1895. It was a huge county, bigger than the states of New Jersey, Maryland, and Delaware combined. Elmore County and Logan County were carved out of Alturas in 1889 by the Idaho Legislature. But what the legislature giveth, it can also take away. In 1895 Logan and Alturas were combined to become Blaine County. Then just a couple of weeks later, the legislature sliced off a sizable piece of that to create Lincoln County.